Generously butter a 1.4 litre (2½ pint) pudding basin. Put the pineapple in the basin, then the ginger and spoon the golden syrup on top.
Mix all the dry ingredients in a large bowl then beat in the egg and milk and mix well. Spoon into the basin, cover with a piece of buttered, pleated, baking paper, then a piece of pleated foil. Secure with string.
Half-fill a large saucepan with water and bring to the boil. Either place the pudding in a steamer compartment over the saucepan or stand the basin on a trivet in the saucepan. Cover tightly with a lid and steam for about 2½ hours, topping up the water level with boiling water every so often.
Leave the pudding to stand for 10 minutes then turn it out onto a warmed serving plate. Spoon over some syrup from the ginger jar or more golden syrup if you like.
Slow cooker method. Check that the pudding basin fits inside your slow cooker with the lid tightly fitting. Prepare and cover the pudding, then stand the basin in the slow cooker and pour in boiling water to come halfway up the sides of the basin. Cover with the lid and cook on high for 4-6 hours.
Serve with coconut and lime sauce: whisk 1 tablespoon cornflour with 160ml can coconut cream, heat gently in a small saucepan, whisking all the time and adding 6–7 tablespoons of the juice from the can of pineapple. Simmer until it thickens slightly, then add the zest from 1 lime and 1–2 teaspoons lime juice to taste.